Preg testing cows is easier than it used to be

Blood tests, manual palpation or ultrasound are all proven techniques to find out if she is, or she isn't. Photo:
Supplied

Most beef producers routinely pregnancy test cows after breeding season, to determine which ones to keep and which ones to sell. It’s a major cost to feed open cows through winter. Another major reason is that finding more than a typical number of open cows can alert you to a disease problem. Trichomoniasis, vibriosis, IBR, BVD, and lepto can cause cows to lose their pregnancies. Nutritional deficiencies can also show up as open cows.

There are several methods available for preg testing, including palpation, ultrasound and blood tests. Dr. Steve Hendrick of Coaldale, Alta., prefers ultrasound, primarily because he’s most experienced with it. “With experience, manual palpation can be very accurate as well. One of the added benefits of ultrasound is that you can sex the fetus. This may be desired by some producers, especially in a purebred herd,” he says.

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“You can also assess viability of the fetus. Being really good at pregnancy testing (and determining stage of pregnancy, etc.) is an art; it’s not all science. There is a lot of variability in size of the buttons (cotyledons), size of the fetus, etc. You have to weigh many factors, the same with ultrasound. You can take measurements such as trunk measurements and crown to rump length, to estimate stage of pregnancy,” he says.

“Most producers are just content to know whether the cow is pregnant or not, but some want to know if she will calve early or late in the calving season, for management purposes, such as sorting the herd for pre-calving scours vaccinations.” Some producers also want to know whether to put a certain cow with an early group (to watch more closely during colder weather) or a later-calving group.

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“Blood testing has a place, particularly for herds that are remote and far from a veterinary service,” says Hendrick. If the veterinarian has to drive for two hours to get there, it will cost more for the farm call. And for a small herd, it may be more cost effective to just draw the blood samples yourself and send them to the lab.

The disadvantage to the blood test is that you must wait two or three days for the results. This is a problem if you need to make the decision immediately on which cows to keep or cull. It’s not a problem if you’ll be handling the cattle again. Blood samples can be drawn, for instance, when a person brings cattle in for pre-weaning vaccination of calves. The results would be available when the cattle are brought back in for weaning, and the open cows could be sorted off at that time.

The method chosen for checking will depend on your management and goals, feed costs and markets. In a drought, you might want to wean calves early and sell cull cows early, to reduce feed costs. “We had a situation here this spring where some producers exposed their cows to a bull before going out to pasture, and did some early preg checking. Grass was slow coming, and they were fairly confident that the cows were far enough along that they didn’t need to put a bull with them when they went to pasture. With the high expense of bulls this year, they wanted to save money. They were having to break groups up into different pastures to utilize other grass and couldn’t run them in one large group. They needed to stretch their bull power, and asked us to preg-check their cows early,” says Hendrick.

Producers need to realize that there’s always a certain amount of early pregnancy loss in every herd. “If you preg check cows early, a few that were determined pregnant are no longer pregnant by calving time. This is true with the blood test, as well. The pregnancy protein lingers in the bloodstream a couple of months after calving, or after an abortion.” If you took the blood sample just after a pregnancy loss it may show as positive or suspect, even though the cow was no longer pregnant.

Checking a cow for pregnancy using manual palpation.photo: Supplied

Extension-arm Ultrasound

The extension-arm probe has been in use about 15 years. The first commercial extension arm units had an oscillating probe so you didn’t have to rotate the rod to view the uterus and its contents.

Dr. Andrew Bronson and his partner Bruce Hill from Alberta then developed an improved version of this technology called Repro-Scan that uses a convex rectal probe that produces a larger image, with more durable equipment.

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“When we started our company, there were no beef ultrasound units available with the convex rectal probe. We created one and put it into a portable case,” says Bronson.

The big advantage to the extension-arm unit is that it is much easier on the person doing the pregnancy testing. Palpation and arm-in ultrasound put a lot of wear and tear on veterinarians who do a lot of this.

“My partner and I preg checked more than 150,000 heifers by ultrasound in 2-1/2 years — when the Canadian border was reopened and nothing pregnant was allowed to be exported. We would not have been able to do this many without extension-arm ultrasound,” notes Bronson.

Regarding cost, Bronson doesn’t charge any more for this service than for palpation. “It does the same job I was able to do with my hand. But if the client wants accurate fetal aging, which takes more time with ultrasound, then I charge more.”

Blood tests

The advantages of the blood test over palpation include being able to detect pregnancy a little sooner with better accuracy. It can be done quickly and easily, taking a blood sample from a vein under the tail, with less trauma to the animal. The BioPRYN test is very accurate on heifers, and on cows that are 90 or more days past calving. If checked too soon after calving, there will still be some PSPB present in the bloodstream, which could result in a false positive.

Today there are nearly 50 labs in North America that process blood samples, including two in Canada. Dr. Bruce Hill at Sunny South Veterinary Services, an animal health supply outlet, located in Lethbridge has been running the BioPRYN tests for more than five year at their BioCheck lab.

“The rancher can bleed the cows, using red-top tubes, then label and mail those tubes to us, by Purolator or Canada Post. The samples don’t need to be kept cool — just wrapped in bubble wrap to protect them from breakage, says Hill.

“We are getting enough samples to run the tests every day, so the turnaround is quick. If we receive the samples by noon, the producer will have the results the same day, by fax or email, whichever the producer prefers. There is a form on our website that can be downloaded, to send it in.” The website is www.biochecklabs.com.

“We can send instructions on how to tail bleed cows if they’ve never done it before, and there are videos on the BioTracking website on how to bleed cows. We also provide the tubes and have pre-made kits we can send out. They contain prepaid Canada Post envelopes, to make it as easy as possible,” says Hill.

“The blood test works well for anyone who has individual ID on their cows. It’s just a matter of bleeding the cows, sending the samples to the lab, and then getting the results back to know which cows are open,” says Hill. It’s easy to collect the samples.

“The test is accurate as early as 28 days after conception. If you have a short breeding season on heifers — such as a 30-day breeding season — you could do this test 30 days after pulling the bull. With a synchronized AI program you can check them 30 days after they are inseminated,” says Hill.

Then you’d know which ones are open, early enough to sell them as open heifers to a feedlot market when the price is best.

“If you only have 30 to 50 heifers to check, and your vet is one or two hours away, the farm call is costly. We have many Hutterite colonies that have used the blood test a lot for their dairies because they are out in the middle of nowhere, two or more hours away from a veterinarian. They preg check and look for open cows every two weeks, so the blood test is less expensive,” he says.

In Western Canada there are two labs that do the BioPRYN test, the Prairie Diagnostic lab in Saskatoon and the BioCheck lab in Lethbridge. A Quebec company is running a DG29 blood test, developed by Conception Animal Reproduction Technologies of Quebec.

Susan Cook runs the WCVM Endocrine Lab of Prairie Diagnostic Services in Saskatoon, and has been doing the BioPRYN test for three years. We don’t get enough samples to do them daily like some of the labs. We set up on Thursdays. There is an overnight incubation and the results are ready by early afternoon on Friday,” she says.

“The rancher could get supplies and collection tubes from their vet; we don’t provide those. The blood tubes and needles are readily available from farm/feed supply stores. There are at least four stores here in Saskatoon where a person could buy needles and tubes,” she says.

“This blood test is more accurate than earlier tests in which we had to measure progesterone (which is a positive non-pregnancy test). I was very happy when BioTracking made its kits available for the BioPRYN test,” Cook says. Samples come to their lab from all over Canada, as far away as Quebec.

“We charge $5 each for the tests. In the last six months, BioTracking has altered the assay just a little so that this same test will work for sheep, as well. We can now do pregnancy tests on sheep and goats if people have dairy goats or purebred sheep they need to check,” Cook says.

The blood samples can be sent by Canada Post or courier. PDS has an agreement with Purolator which makes shipping less expensive. This information can be found on the PDS website, www.pdsinc.ca under Resources, Sample Protocols, Packaging, and Courier Rates. The website lists the PDS services and submission forms, sample protocols and phone number.

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